Synchronized feature patterns of local field potentials in hippocampal-prefrontal cortex during working memory based on time-varying spectral coherence / 国际生物医学工程杂志

Objective:To investigate the synchronized feature patterns of local field potentials in the hippocampus (HPC) and prefrontal cortex (PFC) during working memory based on time-varying spectral coherence so as to support the study of information processing mechanisms in working memory.Methods:The local field potentials (LFPs) signals of the ventral hippocampus (vHPC) and medial prefrontal cortex (mPFC) were collected from six SD rats during the performance of a spatial working memory task in the Y-maze, and the time-frequency distributions of vHPC and mPFC LFPs were calculated by applying the short-time Fourier transform (STFT) to determine the characteristic frequency bands of the working memory and then to investigate the synchronized patterns of vHPC and mPFC LFPs based on the coherent of the time-varying frequency spectrum. Finally, support vector machines were applied to explore the feasibility of applying spectral coherence values to predict working memory.Results:When rats performed working memory tasks correctly, the energy of the theta band (4 - 12 Hz) of the HPC and PFC increased (all P < 0.01), and the spectral coherence value of the theta band of the HPC-PFC increased ( P < 0.05). Support vector machine training and prediction using the average peak spectral coherence and the difference between the peak and the onset when correctly and incorrectly executing the working memory as features resulted in 89% accuracy, 90% precision, 88% recall, and 88% F1 scores, all of which were statistically significant differences compared to the results of the randomly disrupted labeled data rearranging (all P < 0.05). Conclusions:Synchronized synergy in the HPC-PFC theta band is one of the potential mechanisms for correctly performing information processing in working memory.

Intermuscular coupling based on wavelet packet-cross frequency coherence / 生物医学工程学杂志

Human motion control system has a high degree of nonlinear characteristics. Through quantitative evaluation of the nonlinear coupling strength between surface electromyogram (sEMG) signals, we can get the functional state of the muscles related to the movement, and then explore the mechanism of human motion control. In this paper, wavelet packet decomposition and : coherence analysis are combined to construct an intermuscular cross-frequency coupling analysis model based on wavelet packet- : coherence. In the elbow flexion and extension state with 30% maximum voluntary contraction force (MVC), sEMG signals of 20 healthy adults were collected. Firstly, the subband components were obtained based on wavelet packet decomposition, and then the : coherence of subband signals was calculated to analyze the coupling characteristics between muscles. The results show that the linear coupling strength (frequency ratio 1:1) of the cooperative and antagonistic pairs is higher than that of the nonlinear coupling (frequency ratio 1:2, 2:1 and 1:3, 3:1) under the elbow flexion motion of 30% MVC; the coupling strength decreases with the increase of frequency ratio for the intermuscular nonlinear coupling, and there is no significant difference between the frequency ratio : and : . The intermuscular coupling in beta and gamma bands is mainly reflected in the linear coupling (1:1), nonlinear coupling of low frequency ratio (1:2, 2:1) between synergetic pair and the linear coupling between antagonistic pairs. The results show that the wavelet packet- : coherence method can qualitatively describe the nonlinear coupling strength between muscles, which provides a theoretical reference for further revealing the mechanism of human motion control and the rehabilitation evaluation of patients with motor dysfunction.

Research progress on analysis methods in electroencephalography-electromyography synchronous coupling / 生物医学工程学杂志

The motor nervous system transmits motion control information through nervous oscillations, which causes the synchronous oscillatory activity of the corresponding muscle to reflect the motion response information and give the cerebral cortex feedback, so that it can sense the state of the limbs. This synchronous oscillatory activity can reflect connectivity information of electroencephalography-electromyography (EEG-EMG) functional coupling. The strength of the coupling is determined by various factors including the strength of muscle contraction, attention, motion intention etc. It is very significant to study motor functional evaluation and control methods to analyze the changes of EEG-EMG synchronous coupling caused by different factors. This article mainly introduces and compares coherence and Granger causality of linear methods, the mutual information and transfer entropy of nonlinear methods in EEG-EMG synchronous coupling, and summarizes the application of each method, so that researchers in related fields can understand the current research progress on analysis methods of EEG-EMG synchronous systematically.

Comparison of QEEG Findings between Adolescents with Attention Deficit Hyperactivity Disorder (ADHD) without Comorbidity and ADHD Comorbid with Internet Gaming Disorder

Internet gaming disorder (IGD) is often comorbid with attention deficit hyperactivity disorder (ADHD). In this study, we compared the neurobiological differences between ADHD comorbid with IGD (ADHD+IGD group) and ADHD without comorbidity (ADHD-only group) by analyzing quantitative electroencephalogram (QEEG) findings. We recruited 16 male ADHD+IGD, 15 male ADHD-only adolescent patients, and 15 male healthy controls (HC group). Participants were assessed using Young's Internet Addiction Scale and ADHD Rating Scale. Relative power and inter- and intra-hemispheric coherences of brain waves were measured using a digital electroencephalography (EEG) system. Compared to the ADHD-only group, the ADHD+IGD group showed lower relative delta power and greater relative beta power in temporal regions. The relative theta power in frontal regions were higher in ADHD-only group compared to HC group. Inter-hemispheric coherence values for the theta band between F3–F4 and C3–C4 electrodes were higher in ADHD-only group compared to HC group. Intra-hemispheric coherence values for the delta, theta, alpha, and beta bands between P4–O2 electrodes and intra-hemispheric coherence values for the theta band between Fz–Cz and T4–T6 electrodes were higher in ADHD+IGD group compared to ADHD-only group. Adolescents who show greater vulnerability to ADHD seem to continuously play Internet games to unconsciously enhance attentional ability. In turn, relative beta power in attention deficit in ADHD+IGD group may become similar to that in HC group. Repetitive activation of brain reward and working memory systems during continuous gaming may result in an increase in neuronal connectivity within the parieto-occipital and temporal regions for the ADHD+IGD group.